Stalin believed that socialism was only possible in a highly advanced industrialized nation.

Stalin believed that the revolution should serve the working class, and not the peasants like the NEP had done.

Stalin wanted to replace the bourgeois specialists' who managed industry during the NEP with 'red specialists' who were educated by the Communist Government and who were from the ranks of the working class.

Political Causes

In order for Russia to defend itself against capitalist nations, Stalin believed that it would need to develop iron, steel, oil and coal industries on a larger scale, as they were necessary for warfare

Having won the leadership struggle, Stalin no longer wanted to be seen as Lenin's pupil. In 1929 on his 50th birthday, he issued a speech in which he highlighted Lenin's mistakes in regards to the NEP.

Economic Causes

Improvements in the production of commodities such as crude oil still left Russia significantly behind Germany, France and other western nations.

The NEP failed to industrialise Russia, e.g. the amount of iron, steel and copper produced never exceeded the amount produced in the last years of the Tsar